A Summary of Tom Kilburn's Achievements

Here is a summary of Tom Kilburn's achievements, followed by a
shorter version
of the full biography. The links in the summary go to
the shorter version below, and the
headings in the shorter version link to the corresponding headings in the
full biography.

The Computing Service Tom Kilburn takes over
leadership of computer development from F.C. Williams. Computing Service
started for wide range of
organisations (becomes an independent service late 1960s).

MU5
New machine with architecture dedicated to high-level language requirements.
c. 1970 Makes major contribution to new ICL 2900 series
architecture. Working 1972, with major O/S and compiler
production system (under Derrick Morris) fully
operational 1973.

1975-81

Later Years
C.S. department grows and diversifies; (o)100 students/year.

Honours and Awards
(E.g.) 1965 Fellow of the Royal Society; 1973 C.B.E. -- plus many from
Universites and Computer organisations.

Tom Kilburn went to Cambridge University in the war to study Mathematics, and
graduated in 1942 with 1st class honours. On his call-up, he was sent to take
a six-week crash course in Electronics, and then to join
F.C. Williams' group at the
Telecommunications Research Establishment (TRE)
at Malvern. Williams had already made a major contribution to the development
of airborne radar, and now ran a small central group solving electronic problems
for other groups within and beyond TRE. By the end of the war Tom was an
accomplished member of the group.

In December 1946 F.C. Williams left TRE for the University of Manchester,
to take a chair in Electro-technics (later Electrical Engineering). Tom Kilburn
was seconded to Manchester by TRE at the same time to work full time under
Prof. Williams on a prospective storage system for use in electronic
computers. The lack of an effective storage mechanism, that could easily store
both numbers and instructions in a form that could be processed at
electronic speeds, was holding up the development of electronic computers
worldwide. In 1947, Tom Kilburn, under the supervision of Prof. Williams, and
with the assistance of Geoff Tootill,
developed a storage system using a
standard Cathode Ray Tube that could hold 2048 bits with random access. This
overtook the work on other storage systems in the US and UK, and so when the
same team developed a small computer to test the system, the
SSEM, or "Baby", this was the first stored-program
electronic computer to be built and to work, on June 21st 1948.

The "Baby" immediately demonstrated that the storage system was suitable
for computers, and that the stored-program electronic computer was viable.

Rather than add more store to the Baby, the decision was quickly made to
develop it into a full-sized computer; the team was expanded by the inclusion
of three full-time PhD students, and, by October,
the basic design for the
full-sized computer had been completed, and the government had issued a
contract for Ferranti Ltd to manufacture a commercial computer based on it.
Tom formally joined the department, and was awarded a PhD.

The Manchester Mark 1 was completed by October 1949, and
the first Ferranti Mark 1 was delivered in February 1951.
An intermediary version of the Manchester
Mark 1 was available for use in April 1949, with the peripheral equipment still
incomplete. Again Tom Kilburn led the design and building of the Manchester Mark
1. The intermediary version became available at much the same time as the
full-sized EDSAC at Cambridge University (May 1949) and was running long
programs over the summer of 1949. These two computers were the first two
full-sized electronic stored-program computers working in the world.
The Manchester Mark 1 introduced the first
two major extensions to the classical von Neumann architecture described in
1945: address registers (albeit in primitive form) and fast random-access
secondary storage (the "drum", the ancestor of today's hard disc). The address
register meant that it was no longer necessary to program instructions to alter
each instruction that needed to access a store location whose address was not
known when the program was loaded (e.g. an array element). It was some time
before another computer was working with a two-level store (apart from the
Ferranti Mark 1).

Meanwhile the CRT storage system, which became known as the
Williams Tube became one of the
two storage systems that supported (most) computers worldwide until "core
store" became
widely used in the mid-fifties. The first Ferranti Mark 1 was delivered in
February 1951, the world's first production computer (just ahead of the
UNIVAC). In all nine were sold publicly, three of them abroad.

1951 saw some big changes. Once the first Ferranti Mark 1 was working smoothly
effort on it was switched to the software side. The early software for the
Manchester Mark 1 and then the Ferranti Mark 1 had been developed under the
leadership of Alan Turing. But in 1951
R.A. (Tony) Brooker took over. He quickly made
major advances in the quality of the software provision, culminating in the
Mark 1 Autocode in 1954. A large
computing service was built up, used by a
number of universities, industrial firms and government organisations. Also in
1951 F.C. Williams reduced his active involvement in computer development, to
concentrate on Electrical Engineering matters, leaving Tom Kilburn, now a Senior
Lecturer, to run the Computer Group.

The engineering members of the Computer Group now set to work to design and
build two new computers.
MEG was basically a
version of the Mark 1 with floating point arithmetic added, but with improved
techniques it was 30 times faster. MEG first ran in 1954 and was one of the world's
first floating point computers. Ferranti built a production version of it, the
Mercury, using a core store for RAM instead of Williams-Kilburn Tubes. 19 were
built, the first delivered in 1957, and they were a major resource for the
scientific computing in the UK. In 1958 the department acquired a Mercury to
take over the Computing Service from the Mark 1.

The
Transistor Computer was an
experiment in the use of transistors. It had no RAM, with program and data being
stored on a drum. A small version was working by 1953, possibly the first
working transistor computer, and an expanded version by 1955. Six production
versions were built by Metropolitan Vickers, the first delivered in 1956.

In 1956 Tom Kilburn and his team started to look at the design of a machine
that would be far larger and, with transistors and core store now
available, much faster. It was called
MUSE (for
microSEcond) and aimed for
a speed of 1 million instructions a second. This was 1,000 times faster than
the Mark 1 still running the computer service. The innovation required to
achieve this speed, and then to deal effectively with the
implications of it, was massive -- a long list of new features that
bridged the gap between the basic designs of the early '50s and the
sophisticated mainframes of the middle '60s, most obviously multiprogramming.
Although there were two similar projects in the
US with a similar timescale (LARC and the
IBM STRETCH) there was little help to be gained from their progress, and the
detail of the implementation of the new ideas was carried out independently
of them. And of
course the massive improvement in power necessitated an explosion in software
requirements as well -- a large operating system and a large coordinated
compiler suite (given that the international languages FORTRAN, ALGOL and COBOL
had to be considered as well as the local Mercury Autocode and Atlas Autocode).
Both for funding and manpower reasons the department needed help, and this was
provided by Ferranti joining the project in 1959, with the machine renamed
ATLAS. Ferranti made particular contributions on the Operating System side and
manufacturing. Tony Brooker capped his (existing) Mercury and (new) Atlas
Autocodes (high level languages) with the revolutionary Compiler Compiler, a
language for writing compilers in, with built in BNF definition and recognition
facilities.

Atlas first ran in December 1962, with a limited Supervisor, with another year
passing before the Supervisor reached full power. At the time it was arguably
the most powerful and sophisticated computer in the world. The new ideas and
their practical implementation had a significant influence on computer thinking
worldwide, with Virtual Memory and the Compiler Compiler probably the most
important ideas particular to Manchester.
Three full-sized Atlases were built, and three scaled-down versions. As with
the Ferranti Mark 1 and Ferranti Atlas, they provided a major resource for the
UK scientific community.

Once Atlas was running smoothly, Tom Kilburn's next project was to set up a new
department. He had been made a
Professor of Computer Engineering (in the Electrical Engineering department) in
1960, and in 1964 the Computer Group evolved into the new
Department of Computer Science, with Tom Kilburn as its head, now Professor of
Computer Science, with a complement of 12 academic staff. Underneath him were
D.B.G. (Dai) Edwards
in charge of hardware and Tony Brooker in charge of software.
A whole new syllabus had to be produced, with an equal emphasis on hardware and
software. A significant body of undergraduates was built up (around 30 per
year), starting in 1965. This was the first Computer Science department in the
UK, possibly in Europe.

In 1966, with Atlas and the new department and the undergraduate syllabus under
control, Tom Kilburn and his team started work on their next machine,
MU5. With four years of experience of
Atlas acquired, and with the majority of programs being
written in high-level languages, the main focus of MU5 was to provide an
architecture geared to the efficient running of such programs. Amongst the
highlights of
the architecture were an associative name store (to reduce code optimisation),
segmentation (to enable code to
be shared between active processes), and the "descriptor" word; this meant that
the code required to access a data structure element had only to give the basic
operation plus the address of a location holding a description of the structure
(e.g. the array bounds and array element bit size) -- the hardware would do
the rest.

There was no agreement this time for the machine to be manufactured, but the
large Science Research Council grant for MU5 set up a continuing cooperation
with the Ferranti Atlas team, which had been taken over by ICT, and then ICL.
However the MU5 architecture made a major
contribution to the design of ICL's new 2900 series, and so has had a visible
presence long after the department's machine was retired. Tony Brooker left
before the MU5 project got going, so it was Profesor Derrick Morris who led the
software side. This of course made a major contribution to the design of the
architecture, and the software team also created a large innovative operating
system and compiler generating system, both of which were designed to work
across a connected family of disparate machines (ICL1905E, MU5 and PDP11/10
in practice).

MU5 first ran in 1972, and by 1974 the MU5 complex was running as a complete
system, with operating systems and compilers running as planned, and providing
a Computing Service for the staff and students of the department.

MU5 was the last in the progression of main-frame computers designed at the
University of Manchester, evolving continuously from the Baby. It was now the
policy of the department to give up the tradition of having a single major
research project (i.e. a new machine!) taking up most of the effort of most of
the staff.

Tom Kilburn retired in 1981, handing over to his second-in-command ever since
the early 1950s, Professor D.B.G. Edwards. He handed
over a flourishing department, now diversified over a large number of areas of
Computer Science, with around 30 staff and annual intake of over 100 students.